Genetic sequencing has become an increasingly important area of genetic research, promising future uses in diagnostic and other applications. In general, genetic sequencing consists of determining the order of nucleotides for a nucleic acid such as a fragment of RNA or DNA. Relatively short sequences are typically analyzed, and the resulting sequence information may be used in various bioinformatics methods to align fragments against a reference sequence or to logically fit fragments together so as to reliably determine the sequence of much more extensive lengths of genetic material from which the fragments were derived. Automated, computer-based examination of characteristic fragments have been developed, and have been used more recently in genome mapping, analysis of genetic variation between individuals, identification of genes and their function, and so forth. However, existing techniques are highly time-intensive, and resulting genomic information is accordingly extremely costly.
A number of alternative sequencing techniques are presently under investigation and development. These include the use of microarrays of genetic material that can be manipulated so as to permit parallel detection of the ordering of nucleotides in a multitude of fragments of genetic material. The arrays typically include many sites formed or disposed on a substrate. Additional materials, typically single nucleotides or strands of nucleotides (oligonucleotides) are introduced and permitted or encouraged to bind to the template of genetic material to be sequenced, thereby selectively marking the template in a sequence dependent manner. Sequence information may then be gathered by imaging the sites. In certain current techniques, for example, each nucleotide type is tagged with a fluorescent tag or dye that permits analysis of the nucleotide attached at a particular site to be determined by analysis of image data.
Although such techniques show promise for significantly improving throughput and reducing the cost of sequencing, further progress in the speed and reliability of the analytical steps involved in sequencing is desirable.